Someone told me that the four (bass clef) bars above from Bach's Mass in B Minor are a sort of musical joke: the top line reads like a Lutheran chorale and the bottom line reads like a Roman plainchant.  The Latin means "And [I believe] in one holy catholic and apostolic church", so they were saying that Bach was making a statement about church unity.

While I wouldn't put this sort of thing past Bach, I don't know enough about music to tell whether this is true.  Do any of you know?